To be fair to Silverscreen, they do say in the instructions that the screen is only intended for use while camping and warn against use when the van is in storage. I've noticed over the five years we've used a genuine Silverscreen that the outside has 'tarnished', but we've had no real issues and I'll wholeheartedly recommend their product. Communications with Silverscreen both before and after purchase was excellent IME -- but then my discussion with them was gentle and unlikely to end in a demand for compensation. My guess is that the OP has, contrary to the instructions, used the screen for storage over-winter, which has allowed the aluminium reflective treatment to be in contact with the bodywork long enough for it to permanently adhere.
FWIW, I'm always wary of Milenco. At one time they claimed that their towing mirrors were the only ones that could be legally sold in UK when that just wasn't the case (they were the only ones that complied with legislation not yet in force at the time). They tried to tell me the towing mirrors I'd just bought from a competitor were illegal even though my towcar was first registered before the cut-off date and that I must buy their product or face prosecution. When confronted, their rep was very evasive. Despite that, I bought a pair of their "Triple" levelling ramps based on their sales blurb as it seemed nothing else offered the same 'lift'. However, those levelling ramps were rubbish and seriously deformed at first use despite being loaded to only 2/3 design loading -- I ended up with a refund from the shop that sold them, but Milenco themselves were uninterested when I reported the issue. I have no experience of their covers, but my experience with the company suggests caution...
